Electric switch



O I:'t.l3, 1933. w.o.| El-1MAN 1,928,940

'I ELECTRIC swITcH Filed April l, 1931 2 Sheets-Sheet 1 i @A il# @ai Patented Oct. 3, 1933 UNITED ,STATES PATENT ori-lcs 1,928,940 morale swrrcn oonsin Applicants April 1, 1931. serai No. 526,911

15Claiml.

This invention relates to certain new and useful improvements in electric switches and refers more particularly to switches which embody a protective overload feature.

i In its broad aspects this invention issimilar to that described in the copending application of Gustav O. Wilnis, Serial No. 321,317, led November 23, 1928,and is embodied in a switch adapted to be closed manually and opened either manually or automatically, but in which closure of the switch depends upon the position oi a latch element adapted to be moved out oi its operative position -by means responsive to an overload in the circuit in which the switch is ineluded, so that 1t is impossible to han the switch closed and thus defeat its overload protective feature.

It is an object of this invention to improve the construction of switches of this character.

Another object of this invention is to provide a lswitch of the character described in which the circuit is broken at four points to thus assure positiveness of operation. Another object of thisinvention is to provide a switch of the character described, which is of unitary construction and may be mounted in and removed from an enclosing casing as a unit.

And a further object of this invention is to v provide a switch of the character described in which the several elements are comparatively rugged.

And a still further object of this invention resides in the provision of a switch of the character described in which the possibility of-arcover is greatly diminished.

,With the above and other objects in -View which will appear as the description proceeds, my invention resides in the novel construction, combination and arrangement oi parts substantially as hereinafter described and more particularly dened by the appended claims, it being understood that such changes in the precise embodi- 5 ment o1' the herein disclosed invention may be made as come within the scope of the claims.

In the accompanying drawings I have illustrated one complete example of the physical embodimenty of my invention-constructed according 5g to the best mode I have so far devised for the practical application of the principles thereof, and in which:

VFigure 1 is a longitudinal sectional view through u. switch embodying my invention;

' 55 Figure 2 is a view partly in elevation and part- (Cl. 20G-116) 1y in section, taken through Figure l on the plane of the line 2-2;

Figure 3 is a partial side elevation illustrating the position of the various contacts, upon depression of the main actuating button;

Figure 4 is a cross sectional view taken through Figure 2 on the plane of the line 4-4; and

Figure 5 is a view similar to Figure 1 of a portion of the mechanism illustratingthe manner in which the thermally actuated protective device functions. i l

Referring now more particularly to the accompanying drawings, in which like numerals designate like parts, the numeral 6 represents a base on which the switch structure, to be later described, is mounted and which is formed of porcelain or molded insulating material. it two diagonally opposite corners the base 6 has upstanding projections i and 8 to which a mounting strap` 9 is secured by screws 1u passed through openings 75 in the base and threaded in offset side arms 9? on the mounting strap.

rllhe mounting strap 9 is thus disposed above the central portion oi the base and has its ends extended beyond the base to provide means by which the base and the switch mechanism, mounted thereon, may be supported in an enclos ing casing 11, the ends of the mounting strap being secured to inwardly extending lugs`12, car ried by the end walls oi the casing.

A terminal screw 13 mounted at the lower portion oi' the base (with respect to Figure 2) is adapted to have a lead 14 connected therewith, and disposed on the other side oi an insulating barrier 15 projected upwardly from the base adiacent the terminal screw 13, is a second terminal screw 16 to which a-second lead 1'1 is adapted to be connected. The leads 14 and 17 are adapted to be electrically connected to complete the continuity of the circuit in which the said leads are included, bythe switch mechanism now about to be described.

The switch mechanism comprises a pair of sta.-s

'tionary contacts 18 and 19, a pair of movable 100 contacts 20 and 21 electrically connected by a bridge piece 22, and a pair of contactors 23 and 24 adapted to electrically connect the stationary and movable contacts when the contacts and conu1 tactors are in certain relative positions. The stationaryY contact 18 is directly connected with the terminall screw 16 and the stationary contact 19 is connected with the terminal screw 13 through a conductor strip 25 at the under side of the base, a substantially U shaped thermal element 26,

las

2 n ltoccati-o and a conductor strip 27, which, like the strip 25, is disposed beneath the base.

Pls best illustrated in Figure 3, both stationary contacts i8 and i9 are formed or strips of spring metal bent to substantially e shape and securely mounted on the base to extend upwardly therefrom with their .contact portions in substantially perpendicular relation to the base. The movable contacts 2@ and 2l, are as stated, electrically connected by a bridge piece 22 and together there- 'with are carried by an actuator indicated generally by the numeral The actuator 23 is formed of insulatingmaterial being preferably molded a phenol condensation product or the like, and comprises a transverse arm 29 to the outer ends of which the movable contacts 23 and 2l are secured by rivets 3d which also pass through the ends of the bridge piece 22, and e, medialiy disposed head 3l from which a cylindrical stem. 32 i ojects to provide a push button. The cylindri Vstern 32 which forros the push butt bearing sleeve 33 carried and the entire c" i e mounting 9 'ieldably maintained lustrated in Figure l stem projected outwardly oi its bearing by an expansive spring 34 mounted in a formed the head oi the with the cylindrical between the bottom of the tween the Contact surfaces of the fixed and movable contacts being slightly less than the'length of the movable contactors 23 and 24 so that when the movable contacts and the contactors are in certain positions relative to the fixed contacts the ends ol' the contactors will be engaged with the Contact surfaces oi the iixed and movable contacts under spring tennon.

The contactera 23 and 21.1, which may be considered intermediate contacts, are carried by a movable head 38 slidably mounted on the stem 37. The stem 37 and the opening in the head in which. itis received are square or oi other polygonal shape to prevent rotation of thehead 38 about the stem 37. The head 38 is molded from a phenol condensation product or other suitable insulating material and consists of a central substantially square portion 39 from the sides or which arms 40 and 4l project to mount'the contactors 23 and 24 respectively. The member 38 is yieldably urged upwardly from the base 6 'and toward the main actuator by an expansive spring 42 surrouding the stem 37 and confined between the central substantially square portion 39 on the movable member 38 and a mounting plate 43 to which the lstem 37 is xed to be mounted thereby l from the base, the plate 43 being disposed ln a suitable recess in the base 6 and beingsecured therein by a-screw 44.

With the switch open the movable head 38,- is held against the undersurface of .the actuator head 31 so that the contactors 23 and. 24 are not connected with either the stationary or movable contacts. Upon depression of the actuator by its push button portion as illustrated in Figure 3, the movable contacts 20 and 21 and the contactors 23 and 24 are simultaneously moved te 3G on the outer end ol a stern 37 toward the Vbase, but inasmuch as the movable contacts move in advance of the contactors dur-- ing their movement toward the base, engagement of the contactors with the stationary contacts does not complete the circuit. To effect complete S9 closure it is necessary that the movable head 3S carrying the contactors be retained. its depressed position illustrated in Figure l and the actuator released to permit its spring El@ to re'- tract the same to its outermost position at which the movable contacts 20 and 2l engage theadjacent ends of the contactors. lt is noted that the actuator is positively guided in. its movement by the stern 37 by reason. ci' its reception in the fr actuator bore 35. 9U

To hold the movable member 3S in its operenu tive depressed circuit making position, a latch. member G5 is provided. The latch member is pivotally mounted as at e6 between a pair of opstanding lugs or ears 47 i3 and is guided .tor movement by a pair i projected from the plate 423. i extended lrom the latch member f proper and engages a finger 5G carried by movable head 38.'

Trie linger 5G is 'formed by strild portion of a substantially 1U shaped stt bracingthe central portion 39 oi" the arms of the il shaped member or tured to permit the stem 37 to pass 'Engagement of the latch proper 5o upon inward movement of iacilitated by the inclined lead outwardly extended arm 4:9, an spring 52 is disposed a sui" base beneath the out member 15 to yield-.ably tive position.

Under usual conditions, t overload exists in the circuit with which the switch is connected, the latch memset 415 free to function in the described manner, upon the occurrence of an overload condition, the il shaped thermal element 26 which formed of.' a bi-metallic strip, ilexes as illustrated in Ifigure 5 and moves the latch member d5 about its pivotal mounting to disengage the latch proper trom the finger 5o carried by the movable head 38, if the switch is closed, freeing the spring ft2 and permitting the same to open the circuit by projecting the movable head 38 and the contactors carried thereby to its inoperative position.

Upon opening of the circuit the thermal element 36 cools and assumes its normal position permitting the latch member 45 to return to its 130 operative position. It the overload condition is but momentary or has been relieved by the time the switch is again closed, the thermal element will retain its normal position permitting the switch to remain closed, but if the overload condition still exists the thermal element will again deflect and disengage the latch member permitting the switch to open.

To prevent grounding of the circmt by engagement of the thermal element with the latch member, an insulating medium 53 is xedto the outer closed end of the bi-metallic member.

The bi-metallic member, as clearly illustrated in Figures 1 and 5, is mounted on the outer end 145 of a projection 54 on the base, by bolts 55 which. pass through openings' therein and electrically connect the conductor strips 25 and 27 with the ends of the b-metallic member.

` The switch also may be opened manually by depressing a stem 56 projected through an open- @UL EL t;

mi. a small coiled recess in the ci the latch ge the to operais, as long as no T ing 57 in the mounting strap 9 and pivotally connected as at 58 with the outer end of the latch member 45, and a cover 59 is provided to close the open side of the casing 11 and is mounted by screws 60 threaded in the mounting strap 9.

It is noted that the construction of the base, and the movable head 38 carrying the contact-.ors

e is such that the contacts are eectively separated by insulating barriers which cooperate to form arc shields. ".l'hese barriers consist of an upstanding wall 61 on the upper end of the base, the transverse arms 40 and 41 of the head 38 to which the contactors 23 and 24 are respectively secured, and downwardly depending anges 62 on the movable head 38.

It is also noted that the anges 62 on the movable head 38 project from its portion 39 toward the base and engage the same to limit the movement of the movable head 38 and the actuator in closing the switch, and to permit the full movement of the actuator, the base has openings 63 for the reception of the movable contacts. The transverse arm 41, lof the movable head has a raised projection 64 which, when the movable member 38 is in its circuit breaking position, is

` directly beneath an opening 65 in the cover 59 (see Figure 4) to visually indicate that the switch has been opened either manually or by the bimetallic member.

With the switch in circuit making position as 4 illustrated in Figure 1, the circuit extends from the terminal screw 13 through the U shaped loi-metallic member 26 and the stationary contact 19, through the contacter or intermediate contact 24 to the movable contact 20, and through the contactor 23 to the other xed contact 18 with which the terminal screw 16 is directly connected.

Upon release of the latch member either by manual depression of the stem 58 or actuation of the bi-metallic member 26 brought about by an excessive current ilow therethrough, the movable member 38 carrying the contacts 23 and 24 is quickly moved by its urging spring 42 to its position disengaged troniv both the stationary and movable contacts, and as the outer ends ,oi the contacting surface or both the fixed and movable contacts are substantially in the same plane, the ends oi the contactors 23 and 24 leave the same simultaneously. ln this manner, the circuit is broken simultaneously at four points so that a tendency toward arcing is reduced to a minimum, and by reason ol the e'ective insulating barriers the possibility oi arc-over is considerably reduced, and creepage from one terminal to th other is practically impossible.

What l2 claim as my invention is:

l. In an electric switch of the character described adapted to open and closea circuit coinprising a stationary contact, a plurality yoi? movable contacts adapted when in predetermined relative positions with respect to each other and the stationary contact, to electrically connect all oi the contacts and close the circuit, means for moving said movable contacts to said relative positions, and means for releasing one of the movable contacts, for movement out oi engagement with both of its adjacent contacts.v

2. A switch device for opening and closing an electric switch comprising spaced contacts one of which ismovable, an intermediate contact, means movably mounting said intermediate contact, said intermediate contact being movable by the first mentioned movable contact to a position at which, upon a second movement of the ilrst mentioned movable contact, it engages said spaced contacts to close the circuit, means for releasably holding the intermediate contact in said position, means for releasing the intermediate contact for movement out of engagement with said spaced contacts, and means for moving said intermediate contactupon its release.

3. A switch device for opening and closing an electric circuit, comprising a stationary contact, a movable contact movable in a plane spaced i'rom 85 and substantially parallel to the stationary, contact, means normally maintaining the movable contact in a position substantially opposite the stationary contact,'an intermediate movable contact adapted to electrically bridge the stationary and ilrst mentioned movable contacts when in a.v predetermined position, said intermediate contact being movable to said predetermined position uponmovement of the nrst mentioned movable contact out of its normal position, said ilrst` 95 mentioned movable contact moving in advance of the intermediate contact during the movement of the intermediate contact to its predetermined position whereby the circuit is completed only after the ilrst mentioned movable contact is returned to its normal position, means i'or releasably holding the intermediate contact in said predetermined position, means for releasing the intermediate contact for movement out o1 its predetermined position, and means for moving the intermediate contact out of its predetermined position upon its release.

4. ln a switch device adapted to open and close an electric circuit, e. plurality of contacts, said contacts being electricallyengaged to close the circuit when certain ol the contacts are moved to .predetermined positions. means whereby movement oi one oi said certain contacts in two direc- ,tions is necessary to place the cont cts in said predetermined positions, and means operable manuay and upon an overload in the circuit to release one oi said moved contacts i'or substantially simultaneous movement out oi engagement with the other contacts to onen the circuit.

5. ln a switch device adapted to open and close an electric circuit, c. plurality ol contacts, said contacts being electrically engaged to close the circuit when certain ol the contacts are movedto predetermined positions, means whereby movement oi one oi said certain contacts in two directions is necessary to place the contacts in said predetermined positions, releasable means lor holding one oi said moved contacts in its respective circuit closing position, means operable `manually and upon an overload in the oircuitrto release said releasably helolcontuct tor movement out oi circult closing iwsitlou, and means operable upon such release lor simultaneously disengaging said contact from the other ntacts with a snap action. "35

6. i switch device ior closing and opening an electric circuit, comprising a stationary contact, a movable contact, and an intermediate movable contact adapted to electrically engage the stationary contact and nrst mentioned movable contact when in a predetermined position to complete the circuit, means normally maintaining the intermediate contact out of engagement with both the static contact and the first mentioned movable contact, means for simultaneously moving the movable contacts to a position at which the intermediate contact engages the stationary contact, means 'lor releasably holding the intermediate contact in said position, and means for subject to overload conditions in the circuit for holding said intermediate bridslna contacts in operative positions against the action of the urging means.

15. In an electric switch for closing and opening an electric circuit, spaced stationary contacts, electrically connected spaced movable contacts spaced from the stationary contacts, an actuator carryingsaid spaced movablecontacts and having a manually operable push button, means yieldably maintaining'the actuator'and the stationary contacts in apredetermined position with respect to the stationary contacts, intermediate movable bridging contacts adapted' to electrically connect the stationary and movable contacts to close the circuit, means movably mounting said intermediate contacts for movement with the actuator and the movable contacts upon act on of 'the the push button, said intermediate contacts being mil . 1,928,940 4the stationary and movable contacts and means disengaged from the movable contacts during such movement, means yieldably urging the intermediate contacts to a position disengaged from both the stationary and movable contacts, latch means subiectto overload conditions in the cirr y s cuit for releasably holding the intermediate contacts against their urging means in a position endisengagement by their urging means from the stationary and movable contacts whereby the circuit is opened at a plurality of points.

' WILLIAM O. LEHMAN.

iis 

